A commercially available disposable blood pressure sensor includes a sensing element communicating through an opening in the side of a lumen which measures dynamic blood pressure in the cardiovascular system via a catheter and a tubing filled with isotonic fluid. The sensing element includes a strain gauge transducer (for example, the type having resistors ion-implanted in semiconductor material) in which a pressure change is sensed as a resistance change in a resistor bridge. A monitor, connected to the transducer by a wire permanently connected to the disposable unit and a reusable cable, supplies two terminals of the bridge with an excitation voltage, and detects an output signal at the other two terminals. The space between the lumen and the transducer is usually filled with a gel so as to transmit pressure without contact of the transducer with the blood, thereby providing electrical isolation of the patient from the sensing element.